Wave front modifying wave guide system



R. B.ROBERTSON-SHERSBY HARVIE El AL WAVE FRONT MODIFYING WAVE GUIDE SYSTEM June 10, 1952,.

Filed July 31, 1947 Fig.2.

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.S-Harfle 3.0 Mitt- 4 Patented June 10, 1952 ERQNTQ'MIODIFYING aSYSTEM 1?";RirbrtiiLBruceifRubertsoniShcrsbyillarviefiMal- \L-Z .w:IEhisinrentionxelatesatomireiesszaeriali'systems eta (hisnnorezpartieularlyicmmemeii'witharrange- .ementsxbyamhich :tlresradiation cnecepti'omeharac- .t-atei 'istic.zoripolarzdiagramzofranzaerialesystemmp- --erating2at;: ultraehighirequenciesemay\cbe :modidied so zasitofconformiitora particularzrequirement.

' i.i-The obj ectsofztheiimzention zisicprovidmmeans by whiehzthupolari: diagram rrelating 'to anzelec- -troemagnetici waveguide: rifice ZDIQBIIOHI,5IOI'5I&

' ,-;'shown iatfl ilia-iaeing mg i reaterawidtheandesmal-ler :zamplitude "and nentredgnon th'eia ngulariidirec- 'ztinn vd3.

:.-:-Ittwilltreadilwappearfthat eany .iri'egulamcimre x3811" be ;broken.down iinteta. group ;o seine-rava es :comprising a ziundamental :and"virarmo'nics: ac- COI'CIiIigfiQ Fourierfs. etheorem rand Jermaaeseries ofrsymmetrical beams.

These :separa-te beams;tare;gproiiidedmaccarding :mirror refie'ctingzEziMzawavesgzztmay readily ibe=;:ioatoithisinventionbydivertinggpartw ,theeenergy simian aerial ismtem according itoithe-zfinvention .jithewave mathsinto ormntioi azwwvegfiide :orifice vnishorn;zorlarmirrorsnrsiiksE Mzhwavetnonduct- :-;of loneibeam s ayzthat ofabeam 2,; 0 ziorm the second beam .Y- L3 by suitableisshapingiandsidisposi- :tion cot an dielectricsmembeninithe= wazepathzout scif-ion'intoa waveguide orificetorjiornmramirror .ing or reflecting device are divided intoi twamrzsw reflecting surface.

;@Reierring;nowtto-rliliguresffleand iswh-iclrB-show a-a-zsuitableearrangementefonmsermth. (wave uide horn;v :gl Alfihdicatesa e rectangul-amwa geguidecior 311861 with'eam-Hmmnnde:'wave zandvwhicheisefiared :constarrt-iissidifferentiflorinitheiplanesivhichxliesznormal to lithe-1E" WflGtOi be more readily-iunderstood-tembodiments thereunifornr;phase@and will rprovide' axnarrowzibeam;

of will now be describeizlby way of example with reference tOI-l the! accompanying drawings in which:

Figure r'is a: grapwshowing *attypicaliunsymafree firomisecondaryelobesizimthe axi'al===direction (1 :{Of therhorn.

A iblocksomprism atfiiotldielectricmrateria1;:such 415L318 polystyrene;10f:.asubstantiallyvztriangularrcmss metricaipolar diagram requiredfforrrarr aeriai"3fliisectiorris:arrangedxwithinitheqmouthiofzthe:horn

system.

Eigure 2 is a graph sim-iI-ara-to that of Eigure 1 oizshowing :resolution of theaunsymmetricalqpolar rz'dia'gramzinto two symmetrieal-rcomponents.

and extends between opposite side wallsitliereof so as to cover the zone y-z. Its longitudinal or ::.iieiight.-.-zaxis: .therefore,: zlies ipar-allel zwitht the E ssveetor-.;of;the wave. 5 The .block A 6;;has. -nne=zof.-" its .FFiguresIBmnd 4 are longitudinal cross-sectional -.side zsuriacesrin' :contactrwith: one zofytheifiared rand endrelevational views respectively of; awavefguidexhorn-rembodying the invention.

;-Figures 5-:and 6 are cross seetionaltandzfront 1elevationalzviews respectivelyioia reflecting mirmor embodying the-invention.

.;':;Figme;-.. 1*:- indicates at J [Lathe desired polar riritagram 1101' an aerialflsystem A representing sintensitiesand a the corresponding angles. t .This

polar diagramhas alarge amplitude peak II 0 darly displaced fmmthesfirst "walla ofsthe hormimdwill.eauseaarzprogressive iphaserzretardatiom oipithess-mave;zeneiggyapassing zrltherethmughsizcer, oventheizoneay rltzthereby :tprnducesrassecondzheamsin the," i-rectionibtzang-uincerthe-tedimenzrsionzy-eez is zsmaileridiham'w-z .ethisssecond .heam v1:also::hroaden and zofirsmallerasamplititder than 5. hatsin direction -1a.

' fiBytsuitabl-e choice z'ofitheisi-zeiandishapeiof the occurring at arig'le'fliand'thenextends so as t0 prism [6 the separate beamsfipl'nfldedfjmay gbe coverniat progressively 1zfiecreasing amplitude, angles in the rangeeh dz. siSuch polar-diagram, it wfll' rb'elmoted -is lnottsymmetricaliiabnut the direction of maximum amplitude i. e., the angle 0! d1.

Figure 2 indicates how the polar diagram of Figure 1 may be regarded as the resultant of two beams, each symmetrical, one shown at [2 being of narrow width and large amplitude and centhe desired angle.

The above explanation is of simplified character and ignores the higher order waves set up b the discontinuity introduced by the block 15; These higher order waves affect the power distered upon the angular direction d1 and the other 55 tribution across the aperture to some extent and plied to a reflecting mirror.

appear to intensify the effect of the dielectric member.

The introduction of the prism It may result in an undesired broadening of the major amplitude beam due to reduction of the aperture dimension .ry providing this beam. This may.

be corrected by the provision of a further convergent dielectric lens as shown at I! spanning the aperture :cy. This convergent lens may, if desired, be combined with the prism 16 to form a single dielectric member. Such convergent dielectric lens members are known and per se form no part of the present invention.

Figures and 6 show another embodiment apl8 indicates a reflector shaped as part of a paraboloid at the focal point [9 of which is located a suitable E. M. wave feeding member in the form of a waveguide orifice or horn 20. The major part of the energy provided by the feed member 20 emerges after reflection by the mirror surface l8, as a narrow beam of high intensity in the direction al. A portion of the reflected energy however, i. e., that intercepted by a prism 2| disposed in front of the mirror surface, is scattered to form a broad beam of small amplitude in the direction bl, i. e., divergent from the main beam al. Such an arrangement can be made to provide a polar diagram similar to that illustrated in Figure 1.

It is necessary to choose the prism dimensions and also its position as shown by the dimension m with respect to the main aperture dimension ,n' so that the two beams combine in the proper phase relationship over the region where they overlap.

The above described arrangement relies upon normal reflection and diffraction for producing the broadened and diverted beam. Further increase in the angular coverage provided by the mirror surface or the like may be obtained by using partial internal reflection from the front face Zla of the prism to produce another broad beam emergent from the lower face of the prism.

The invention is not limited to the direct association of the dielectric member with a wave guide horn or reflector as above described. The dielectric member may be displaced from the horn or mirror by any desired distance provided it falls within the zone illuminated by the energy passing into 'or out of the waveguide or modifying means.

2. An ultra high frequency antenna system for producing a radiation pattern having asymmetric'al characteristics in a chosen plane comprising a principal field modifying means havin a hollow surface producing a symmetrical radiation pattern in the chosen plane and at least one secondary field modifying means having a symmetrical radiation pattern in said plane, said individual symmetrical patterns combining to form a desired asymmetrical pattern in said plane and an electric lens means positioned in the path of energy projected from said principal modifying means and combined with said secondary field ,modifying means in a single structure, said lens being so positioned with respect to said radiator as to focus energy rays received therefrom.

3. An ultra-high frequency antenna system for producing an asymmetrical radiation characteristic in a chosen plane and comprising a radiating device having a substantially symmetrical radiation characteristic per se in said chosen plane, a dielectric block positioned in the path of a portion of the energy leaving said radiating device and extending in a direction perpendicular to said chosen plane, said dielectric block having a prisimatic cross-section in said chosen plane, said radiating device comprising a wave guide horn terminating a rectangular wave guide adapted to convey electromagnetic waves of H10 mode and wherein said horn is flared in a plane lying normal to the E vector of the electromagnetic wave and in which said dielectric material extends in a direction parallel to said E vector and a dielectric lens positioned in the path of at least a portion of the electromagnetic energy leaving said wave uide horn.

4. The combination set forth in claim 3, in which said dielectric lens is combined with said dielectric block to form a single structure.

5. The combination set forth in claim 4, said dielectric block being arranged with one of its surfaces in contact with one of the flared walls of said horn.

ROBERT BRUCE ROBERTSON SHERSBY-HARVIE. RICHARD G. GARFITT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS FOREIGN PATENTS Country Date Germany June 24, 1939 Germany May 31, 1941 Number Number 

